Orb-web, no web: unusual mating behaviours in an orb-web spider

The evolution of the orb-web was associated with a major radiation in spider diversity. The major functions of orb-webs are prey capture and as substrates for courtship and mating. However, the use of orb-webs has associated costs, and the modification and loss of orb-webs has evolved multiple times. While variation between species is evident, such as reductions in or loss of the orb-web for foraging, this kind of variation within species is rarely seen. Here, I describe laboratory observations of foraging and mating without an orb-web in a typical orb-weaving spider, the Australian garden orb-weaver (Hortophora biapicata). I discuss these behaviours, which are likely cases of opportunistic plasticity, in an ecological and evolutionary context. Further investigation of these rare and unusual behaviours may provide unique insights into the function and origin of important traits associated with the orb-web, and the evolution of extended phenotypes.